1. Field of the Invention
This invention relates generally to determining linear position and, more particularly, to using digital means for determining linear position.
2. Description of Related Art
This invention relates to determining linear position by using the electrical outputs of a Linear Variable Differential Transformer (LVDT). It may be desirable to determine a linear position for many applications, for example, actuation systems on aircraft or rocket motors. One method of doing this is to use a LVDT to sense the position. The LVDT may use a sinusoidal excitation and measurement of two inductively coupled output signals. LVDTs have one primary winding and two secondary windings. The two secondary windings are mechanically arranged so an excitation signal on the primary winding will proportionally couple onto the secondary windings based on the position of a ferrous core. By measuring the voltages on the secondary windings it is possible to determine the linear position of the LVDT.
These output signals from the two secondary windings are generally analog signals, which may require a significant amount of analog electronics to evaluate the signal amplitudes and derive the shaft position. As a result, many proposals use analog-to-digital converters to convert the analog signals to digital signals, which may then be manipulated digitally to determine the respective amplitudes and calculate arithmetic functions to determine the shaft position. However, even these solutions may require complex analog-to-digital converters, and complex arithmetic engines for determining the signal amplitudes.
There is a need for a method and apparatus that reduces the complexity and number of analog components used in determining linear position by using simple analog components coupled to flexible digital logic and digital signal processing.